Dual Output Power supply

[technodruid]

Hi all, just a quick question:

I would like two positive voltages output of my power supply I'm designing. Is it OK to wire two secondaries to separate circuits? Or are these transformers required to be wired in series with a center tap?



The reason I ask is I am not in need of a +/- supply for the time being, and wish to test circuits ideas which require differing positive voltages.

OR

If I want dual, and it is better for the transformers to be wired series/parallel, would it be best to have two transformers? One for each output and have two sets of +/- outputs?

[Kleinstein]

One can normally use the secondaries like separate supplies. However the isolation voltage between the secondaries may be limited. So some 50 V between the secondaries is usually OK, but not 500 V without special specs for the transformer.

It is often easier to build 2 identical regulators and thus allow them to be connected as a +- supply of with a common negative side.

[technodruid]

Thanks, so if I'm looking at a 50VA transformer with two 25V secondaries, it should be safe for isolation?

[Kleinstein]

A 2x25 V transformer should be safe for series or "parallel" connection. Also in more normal use a parallel configuration directly of the coils a real option - so the transformer has to be OK with this. Having the connection only behind rectifiers is not that different.